Signatures of Inhomogeneity in the Early Universe

Abstract

We have made a systematic study of the production of elemental CNO in inhomogeneous nucleosynthesis, investigating a much larger region of parameter space than previously studied. We have determined abundances of CNO elements and ascertained the main channels to their production. We have focussed in particular on the role played by the ⁷Li(n, γ)⁸Li(α,n)¹¹B(n, γ)¹²B(β ^- v)¹²C reaction sequence: in models with Ω_b = 1, we show that this sequence provides the main channel to CNO element production of which there is a significant amount; for lower values of Ω_b there is competition from ⁷Li(α, γ)¹¹B but here there is a concurrent decline in CNO production. From these determinations, CNO element production emerges as a distinct signature of an Ω_b = 1 inhomogeneous universe. Beyond ¹²C, a series of neutron captures is thought to lead to the production of ¹⁴C. We have studied the branching at ¹⁴C and have deduced the importance of the ¹⁴C(d, n)¹⁵N reaction which may be the dominant channel for the production of heavier elements.